TL;DR: Aetna, a CVS Health company, modified CPB 0703 on November 26, 2025, reaffirming that thermal perfusion probes for monitoring regional cerebral blood flow are experimental and not covered — meaning any claim under CPT 0042T or the 61000–64999 neurosurgery range tied to this technology will be denied.
If your team bills neurosurgical monitoring for Aetna patients, this policy affects you directly. Here's what changes and what your billing team needs to do before submitting another claim.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | Aetna, a CVS Health company |
| Policy | Thermal Perfusion Probe for Monitoring Regional Cerebral Blood Flow |
| Policy Code | CPB 0703 |
| Change Type | Modified |
| Effective Date | November 26, 2025 |
| Impact Level | Medium — affects neurosurgery and neurocritical care billing teams |
| Specialties Affected | Neurosurgery, Neurocritical Care, Neuromonitoring, Trauma Surgery |
| Key Action | Flag thermal perfusion probe services in your charge capture system and stop submitting CPT 0042T or neurosurgery-range codes for this indication without a denial management strategy in place |
Aetna Thermal Perfusion Probe Coverage Criteria and Medical Necessity Requirements 2025
The Aetna thermal perfusion probe coverage policy under CPB 0703 is simple. There is no covered indication. Aetna does not recognize thermal perfusion probe monitoring of regional cerebral blood flow as meeting medical necessity under any clinical scenario.
That includes the patients you'd expect to see this used for — traumatic head injury, subarachnoid hemorrhage, and post-neurosurgical monitoring. Aetna's position is that the clinical evidence doesn't support routine use of this technology in managing acute neurological disorders.
Prior authorization won't save these claims. No prior auth approval changes the experimental designation. If your team has been requesting prior auth for thermal perfusion probe services and getting approvals, those approvals don't guarantee reimbursement — Aetna can still deny on experimental grounds even after a prior auth is issued. Talk to your compliance officer if you've received prior auth approvals for this service with Aetna.
The coverage policy references CPB 0663 (Cerebral Perfusion Studies) as a related bulletin. That policy governs CT-based cerebral perfusion analysis under CPT 0042T — a different clinical approach, but one that billing teams sometimes conflate with thermal perfusion probe monitoring. They're not the same, and conflating them on a claim creates a clean path to a claim denial.
Aetna Thermal Perfusion Probe Exclusions and Non-Covered Indications
Aetna classifies thermal perfusion probe monitoring as experimental, investigational, or unproven. That language has a specific meaning in payer policy — it's not a soft hedge. It means Aetna won't pay for it, period.
The non-covered indications include all acute neurological disorders where this technology might be deployed clinically: head injury, subarachnoid hemorrhage, and post-neurosurgical monitoring. The policy doesn't carve out exceptions for severity, monitoring duration, or care setting.
The basis for the experimental designation is insufficient clinical evidence. Aetna's position is that the published literature doesn't establish the clinical value of thermal perfusion probe monitoring well enough to support routine coverage. That's a high bar to clear — and this policy has not cleared it.
This is a broad exclusion. Aetna doesn't limit it to specific probe types, manufacturers, or procedural approaches. Any thermal perfusion probe used to monitor regional cerebral blood flow falls under this designation. If you're billing for this service for Aetna members — inpatient, outpatient, or ICU — expect denial.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| Thermal perfusion probe monitoring — head injury | Not Covered / Experimental | CPT 61000–64999 range | No prior auth pathway overrides experimental designation |
| Thermal perfusion probe monitoring — subarachnoid hemorrhage | Not Covered / Experimental | CPT 61000–64999 range | Explicitly listed as excluded indication |
| Thermal perfusion probe monitoring — post-neurosurgical | Not Covered / Experimental | CPT 61000–64999 range | All post-surgical neuromonitoring via thermal probe excluded |
| Cerebral perfusion analysis via CT with contrast (CPT 0042T) | Related — see CPB 0663 | CPT 0042T | Referenced as related policy; billing guidelines differ from CPB 0703 |
Aetna Thermal Perfusion Probe Billing Guidelines and Action Items 2025
This policy is not new — CPB 0703 has covered this technology for several years — but the November 26, 2025 modification is a signal to audit your current billing practices now. Here's what your team needs to do.
| # | Action Item |
|---|---|
| 1 | Audit your charge capture for CPT 0042T and the 61000–64999 range. Flag any line items where thermal perfusion probe monitoring drove the service. These are your exposure points. Pull 90 days of claims submitted to Aetna against these codes and check the clinical documentation behind each one. |
| 2 | Check your denial logs for this indication. If you've been getting denials under this policy without recognizing the pattern, you have a secondary appeals problem. Review any denials with a "experimental/investigational" remark code against Aetna claims in the neurosurgery range — those may trace back to CPB 0703. |
| 3 | Stop submitting thermal perfusion probe services without a denial management plan. This doesn't mean stop providing the service. It means your billing team needs a clear workflow: document the service accurately, note the payer's coverage policy, and route the claim through your appeals process if you believe medical necessity exists. |
| 4 | Do not conflate CPT 0042T (CT-based cerebral perfusion) with thermal probe monitoring. CPT 0042T falls under CPB 0663, not CPB 0703. Billing 0042T for a thermal perfusion probe service — or vice versa — creates a coding accuracy problem on top of a coverage problem. Make sure your coders understand the distinction. |
| 5 | Separate thermal perfusion probe charges from other neuromonitoring services on the same claim. If thermal probe monitoring occurs alongside covered neurosurgical monitoring services, unbundle cleanly. A bundled claim where the thermal probe service gets mixed in with covered services is a denial risk for the entire claim. |
| 6 | Brief your neurosurgery and neurocritical care teams on the billing implications. Physicians ordering or performing this monitoring need to understand that Aetna considers it experimental. If they're generating documentation that assumes coverage, your billing team inherits the denial exposure. Align before the service is rendered, not after. |
| 7 | If you're uncertain how this applies to your patient population or payer mix, loop in your compliance officer before November 26, 2025 is too far in the rearview. The effective date has passed. Your compliance exposure started then. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Thermal Perfusion Probe Monitoring Under CPB 0703
CPT Codes Referenced in CPB 0703
| Code | Type | Description |
|---|---|---|
| 0042T | CPT | Cerebral perfusion analysis using computed tomography with contrast administration, including post-processing |
| 61000–64999 | CPT Range | Nervous System / Surgery (neurosurgery range) |
Note: CPT 0042T is listed as a related code — it falls primarily under CPB 0663 (Cerebral Perfusion Studies). The 61000–64999 range captures neurosurgical procedures broadly. Thermal perfusion probe monitoring billed within this range under any of these codes is subject to the experimental designation in CPB 0703.
Key ICD-10-CM Diagnosis Codes Referenced in CPB 0703
These diagnosis codes appear in the policy's code set. They represent the clinical conditions where thermal perfusion probe monitoring might be clinically considered — and where Aetna's non-coverage determination applies.
| Code | Description |
|---|---|
| E75.0 | Disorders of sphingolipid metabolism and other lipid storage disorders |
| E75.10–E75.19 | Disorders of sphingolipid metabolism and other lipid storage disorders (subcategories) |
| E75.2, E75.23–E75.25, E75.29 | Disorders of sphingolipid metabolism and other lipid storage disorders |
| E75.3–E75.9 | Disorders of sphingolipid metabolism and other lipid storage disorders |
| G00.0–G09 | Inflammatory diseases of the central nervous system |
| G11.0–G12.9, G13.8 | Systemic atrophies primarily affecting the central nervous system |
| G20.A1–G26 | Extrapyramidal and movement disorders |
| G30.0–G32.89 | Other degenerative diseases of the nervous system |
| G35–G43.919 | Demyelinating diseases of the central nervous system and episodic and paroxysmal disorders |
| G45.0–G45.9 | Transient cerebral ischemic attacks and related syndromes |
| G46.0–G46.8 | Vascular syndromes of brain in cerebrovascular diseases |
| G80.0–G83.9 | Cerebral palsy and other paralytic syndromes |
| G90.01–G91.9 | Other disorders of the nervous system |
| G93.7, G93.89, G93.9, G94 | Other disorders of the nervous system |
| G95.0–G95.9 | Other disorders of the nervous system |
| G99.0, G99.2 | Other disorders of the nervous system |
| I60.00–I66.9 | Cerebrovascular diseases |
| I67.1–I67.2, I67.4–I69.998 | Cerebrovascular diseases |
| S02.0xx+–S02.413+, S02.60x+–S02.92x+ | Fracture of skull and facial bones, with or without intracranial injury |
| S06.0X0A–S06.A1XS | Intracranial injury, excluding those with skull fracture |
| S06.0XAA–S06.9XAS | Intracranial injury, excluding those with skull fracture |
| Z13.850 | Encounter for screening for traumatic brain injury |
| Z13.858 | Encounter for screening for other nervous system disorders |
The ICD-10 set here is broad — covering everything from TBI and stroke to sphingolipid disorders and cerebral palsy. The policy isn't saying these diagnoses are all non-covered in themselves. It's saying that thermal perfusion probe monitoring is non-covered regardless of the underlying diagnosis driving the monitoring need.
Get the Full Picture for CPT 61000
Track this policy across versions, search 1,500+ policies by CPT code, and get real-time alerts when any payer changes coverage.